This invention relates to a method and apparatus for resecting a distal femur and a proximal tibia in preparation for implanting a partial knee prosthesis.
Partial knee replacement surgery has become relatively common, and according to traditional practice, requires a relatively large incision in the patient in order to realign the patient""s leg, remove any diseased bone and cartilage, and provide a proper surface for engagement with the tibial and femoral prostheses which must mate to form the partial knee replacement. Such large and complicated incisions increase surgical time and risk and also lengthen patient recovery. Accordingly, more recently minimally invasive techniques have become available, which greatly reduce the size of the required incision, thus providing more rapid healing and recovery for the patient. The instruments used in minimally invasive surgery clearly must be relatively small and are preferably uncomplicated, due to the space constraints within the knee. Further, these instruments must permit alignment of the knee and the proper preparation of the implant surfaces in order to receive and retain the prostheses.
When a patient""s knee deteriorates, cartilage wears away, and the patient becomes bow-legged (or knock-kneed), depending upon which side of the knee is diseased. Accordingly, instruments must be used to reset the spacing between the distal femur and proximal tibia receiving the partial knee implant, to correct bow-leggedness and the patient""s knock-knees. Overcorrection must be avoided, in order to avoid wear (and eventual deterioration) of the side of the knee not receiving the partial knee prosthesis.
The present invention provides a resecting kit which includes multiple spacers, each of which has a different spacing dimension. A surgeon selects the appropriate spacer with the amount of correction desired to align the patient""s leg and installs the spacer with the spacing dimension between the distal femur and proximal tibia on the side of the knee which is to receive the partial knee prosthesis. The spacers have projecting stems, upon which a resector is installed in such a way that the resector may pivot around the stem. The resector is then aligned with the axis selected by the surgeon according to known methods, and is pinned to the femur and proximal tibia. A cut is then made in the femur after which the resector is removed while leaving the tibial pins in place, the pins being headless pins. A second resector is then installed on the pins to effect the required cut of the tibia. Other cuts are made in the femur according to known procedures, and the prostheses are then installed according to known procedures.
Accordingly, since they are relatively small, the spacers are relatively easy to install between the proximal tibia and distal femur. The spacers include a recess to clear the anterior tibial rise, such that the spacer is fully engaged both with the corresponding condyle and the tibial plateau where the prostheses are to be implanted. Since the spacers have no moving parts, minimal manipulation of the instruments within the saggital plane is required.